Over the years, advances in hydraulic fracturing techniques used in oil and natural gas fields has required conveyance of large volumes of frac sand, proppants, or other abrasive materials through piping. For example, frac sand used in hydraulic fracturing is typically hauled in large quantities in trailers but first the sand must be conveyed to the trailer. Oftentimes, large diameter metal piping or fill tubes, that are welded or otherwise permanently attached to the trailer, are used to convey the abrasive frac sand into the trailer. Due to the abrasive nature of the frac sand, the metal piping or fill tubes are subjected to constant wear.
Although more cost effective replaceable rubber liners or inserts may be used within the metal piping, static electricity may be generated when the frac sand flows through the rubber liner. Specifically, as the sand flows through the rubber liner the collision between sand particles generates friction and creates minute amounts of electrical charge. The amount of charge increases as the flow rates and volumes increase. Electrical discharges in oil and natural gas fields are undesirable and, thus, electrically grounding the rubber liner is highly desirable. Further, due to the abrasive nature of sand, the rubber liner will wear and any electrical grounding built into the liner may be compromised. Thus, it is desirable to replace the liner prior to the electrical grounding of the liner becoming compromised.